Fast linkup arbitration

Abstract

A data processing system comprising: first and second network ports each operable to support a network connection configured according to one or more of a predetermined set of physical layer protocols; and a processor configured to, on a network message being formed for transmission to a network endpoint accessible over either of the first and second network ports: estimate the total time required to, for each of the predetermined set of physical layer protocols, negotiate a respective network connection and transmit the entire network message over that respective network connection; select the physical layer protocol having the lowest estimate of the total time required to negotiate a respective network connection and transmit the network message over that respective network connection; and configure at least one of the first and second network ports to use the selected physical layer protocol.

The invention claimed is: 
     
       1. A second network node comprising:
 first and second network ports each operable to support a network connection configured according to one or more of a predetermined set of physical layer protocols, said first and second network ports being physically connected to corresponding network ports of a first network node by respective physical links such that, in a first mode, physical links are made between the first and second network ports and the corresponding network ports on the first network node such that a first network message is received at at least one of the first and second network ports, and in a second mode, both the first and second network ports are isolated from the corresponding network ports on the first network node; 
 a memory configured to store information representing a header for the first network message; and 
 a processor configured to convert the first network message into a data packet using the information representing the header, 
 wherein the first network port is configured to receive network messages over one of the physical links from its corresponding network port according to a first physical layer protocol, 
 wherein the second network port is configured to receive network messages over one of the physical links from its corresponding network port according to a second physical layer protocol different from the first physical layer protocol. 
 
     
     
       2. A second network node as claimed in  claim 1 , wherein the processor is further configured to process the data packet to complete the headers. 
     
     
       3. A second network node as claimed in  claim 2 , wherein the processing the data packet comprises calculating checksums. 
     
     
       4. A second network node as claimed in  claim 1 , wherein the memory is configured to store information representing headers for data packets according to the predetermined set of physical layer protocols, wherein the processor is configured to convert the received network messages into data packets using the information representing headers for data packets according to the predetermined set of physical layer protocols. 
     
     
       5. A second network node as claimed in  claim 1 , wherein at least some of the physical layer protocols of the predetermined set of physical layer protocols are of the same type of physical layer protocol but defined so as to operate at different line speeds. 
     
     
       6. A second network node as claimed in  claim 1 , wherein said processor is configured to convert the first network message to a further protocol. 
     
     
       7. A second network as claimed in  claim 6 , wherein said processor is configured to cause the first network message according to the further protocol to be transmitted over a network. 
     
     
       8. A second network node as claimed in  claim 1 , wherein the second network node is configured to receive in parallel said first network message over both of a first of said physical links and a second of said physical links. 
     
     
       9. A second network node as claimed in  claim 8 , wherein the processor is configured to remove duplicate network messages that arrive after the first received copy of the first network message. 
     
     
       10. A second network node as claimed in  claim 8 , wherein the second network node comprises a network interface device, said network interface device configured to remove duplicate network messages that arrive after the first received copy of the first network message. 
     
     
       11. A second network node as claimed in  claim 1 , wherein the network messages each comprise a sequence number, wherein the processor is configured to use the sequence number to identify duplicate network messages that are to be discarded. 
     
     
       12. A second network node as claimed in  claim 1 , wherein the first physical layer protocol and the second physical layer protocol are any of 100BASE-TX, 10GBASE-T and Serial RS-485, and physical interfaces of the first and second network port are Ethernet RJ45. 
     
     
       13. A second network as claimed in  claim 1 , wherein the processor is configured to cause the data packet comprising the header and the first network message to be transmitted over a network. 
     
     
       14. A second network node as claimed in  claim 1 , wherein the first network message comprises a first timestamp, wherein the processor is configured to:
 following arrival at the second network node of the first network message, determine a second time stamp for the first network message; 
 determine, by comparing the first time stamp and the second time stamp, an indication of the latency associated with transmitting the first network message from the first network node to the second network node according to a physical layer protocol used for the transmission of the first network message; and 
 transmit the determined indication of the latency to the first network node. 
 
     
     
       15. A second network node as claimed in  claim 14 , wherein the second time stamp is determined upon arrival of the first network message at the second network node. 
     
     
       16. A second network node as claimed in  claim 14 , wherein the processor is configured to decompress the first network message, wherein the second time stamp is determined upon completion of the decompression of the first network message. 
     
     
       17. A system comprising:
 a second network node according to  claim 1 ; and 
 the first network node, wherein the first network node has a second plurality of network ports, wherein said second plurality of network ports are connected to respective ones of said physical links, the first network node comprising a second processor configured to transmit said network messages over the physical links. 
 
     
     
       18. The system as claimed in  claim 17 , wherein the processor of the second network node is configured to convert the first network message to a further protocol, wherein the second processor is configured to select a physical layer protocol from the predetermined set of physical layer protocols for transmission of the first network message in dependence on time associated with performing the conversion to the further protocol. 
     
     
       19. A method for use in a second network node comprising first and second network ports and a processor, each of said first and second network ports operable to support a network connection configured according to one or more of a predetermined set of physical layer protocols, said first and second network ports connected to corresponding network ports of a first network node by respective physical links such that, in a first mode, physical links are made between the first and second network ports and the corresponding network ports on the first network node such that a first network message is received at at least one of the first and second network ports, and in a second mode, both the first and second network ports are isolated from the corresponding network ports on the first network node, said method comprising:
 storing in a memory, information representing a header for the first network message; 
 converting the first network message into a data packet using the information representing the header; 
 receiving at the first network port, network messages over one of the physical links from its corresponding network port according to a first physical layer protocol; and 
 receiving at the second network port, network messages over one of the physical links from its corresponding network port according to a second physical layer protocol different from the first physical layer protocol.